This gives the conversion factors used to estimate carbon emissions from various
forms of transport, including air freight. There is a difficulty in calculating
the carbon emissions caused by ari cargo carried as belly freight, in passenger
planes. The document goes into this in some detail. Emissions from dedicated
air freighters are simpler to calculate.

DEFRA produced some figures in 2005, to estimate the carbon emissions from air
freight, giving conversion figures for domestic, short haul and long haul traffic.

These were re-done in April 2008, and a new document produced. It can be found
at:

The way that total kilograms of CO2 are calculated is by multiplying the total
tonne kilometres (eg. 2 tonnes of cargo being transported 3,000 kilometres –
6,000 tonne kilometres) x a figure calculated by DEFRA for the kilos CO2 per tonne
kilometre x a kilometre uplift figure (the IPCC requires this, to take account
of the fact that planes will not fly in a straight line, my have to stack and
circle before landing, and other ways in which more fuel is used – the figure
is estimated to be another 9%). The total gives the kilos of CO2 that have been
produced in flying the cargo.

There are different conversion factors for domestic, short haul (under 3,700
kilometres) and long haul flights, to take account of the proportion of the flight
that is take-off and landing (when more fuel is used that while cruising at altitude).

Total tonne kg CO2 per km uplift

km travelled x tonne km x factor = Total
kg CO2

Domestic x 1.898 x 109% =

Short-haul international x 1.316 x 109% =

Long-haul international x 0.606 x 109% =

( long haul is over 3,700 kilometres)

So, for example,

Eg. 2 tonnes carried for 1,000 kilometres within the UK is:

2,000 x 1.898 x 109 % = 4,138 kg CO2

or

2 tonnes carried for 5000 kilometres is:

10,000 x 0.606 x 109% = 6,605 kg CO2

By comparison, the DEFRA figure given for freight carried by a diesel train would be a conversion factor of 0.021 kg CO2 per tonne kilometre.

Eg. 2 tonnes carried for 1,000 kilometres is:

2,000 x 0.021 = 42 kg CO2 (compared to 4,138 kg CO2 for the plane)

By comparison, the DEFRA figure for freight carried in a small container ship (deadweight 2,500 tonnes) is 0.015 kg CO2 per tonne kilometre (or a small
bulk carrier it is 0.011)